/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [http://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
package org.neo4j.kernel.impl.transaction.log.entry;

import java.io.IOException;
import java.nio.file.Path;

/**
 * Used to signal an incomplete log header, i.e. if file is smaller than the header.
 * This exception is still an {@link IOException}, but a specific subclass of it as to make possible
 * special handling.
 */
public class IncompleteLogHeaderException extends IOException {
    public IncompleteLogHeaderException(Path file, int readSize, int expectedSize) {
        super(template(file, readSize, expectedSize));
    }

    public IncompleteLogHeaderException(int readSize, int expectedSize) {
        super(template(null, readSize, expectedSize));
    }

    private static String template(Path file, int readSize, int expectedSize) {
        StringBuilder builder = new StringBuilder("Unable to read log version and last committed tx");
        if (file != null) {
            builder.append(" from '").append(file.toAbsolutePath()).append('\'');
        }
        builder.append(". Was only able to read ")
                .append(readSize)
                .append(" bytes, but was expecting ")
                .append(expectedSize);
        return builder.toString();
    }
}
